trans/heater vacuum link?

gunforhire · #1 (**permalink**) 12-16-2006, 05:03 PM

Greetings everybody. I'm new to the forum and was wondering if one of you well edu-macated jeep fiends could lend a hand.

It's starting to get cold here in the northeast and 94 YJ is having some heater issues. Specifically, when I set the heater to ‘warm’, well, it’s just not that warm. That aside, it also seems that whenever the heater is on, my transmission (3 speed auto) gets finicky and has trouble engaging from a
dead stop.

I guess my question is, does the transmission have a vacuum control that might be linking these problems or are these unrelated?

Digging around inside the dash board I found what CHILTON calls the ‘Air Door Motor Switch’. And I noticed that this is a three pronged vacuum port, however mine only has two lines connected. Is this intentional or am I creating a vacuum leak that is giving me trans. trouble when I turn on the heat?

Any thoughts are greatly appreciated.

LVRockCrawler · #2 (**permalink**) 12-16-2006, 10:31 PM

first off, welcome to Jeepz!! you'll like it here - now for your problem.... did you have any tranny prob's b/4 turning the heat on? just seems like a weird association between the two systems... try plugging the switch vac lines one at a time and maybe that will help narrow it down to the culprit.... i hate vac. problems as much as electrical ones... good luck and welcome again - maybe others have more to offer.. i try....

jay79cj7 · #3 (**permalink**) 12-17-2006, 12:23 AM

I am not sure but that 3 way connector with 2 hoses does not sound right. Hook a hose to that bare nipple and run it out to the cabin so you can tell if it is pulling a vacuum when you are manipulating the heater controls.

Sparky-Watts · #4 (**permalink**) 12-17-2006, 05:38 AM

First off, Welcome to Jeepz!! Glad to have you aboard!! Just sit back and relax a spell, and we'll have this figured out for you pretty quick. In my '94, I was having some problems with the blend door, and it turned out to be vacuum related. I remember seeing only two lines going from the main vacuum connector to the heater blend door, but there were three holes......hmmm.....that's got me thinking. Now that I think about it, my defroster doesn't ever quit blowing air. I'm wondering if I'm missing a hose as well. Anywho, I'll take a look at mine and see if I can figure anything out for ya, once it warms up and gets light outside.